The invention relates to medical devices, and, in particular, to connectors for tubular medical devices such as catheters and needles.
Catheters are flexible tubes used for withdrawing fluids from or injecting fluids into a patient""s body. Catheters can be used to introduce or withdraw fluids from, for example, a body cavity, duct, vein, or artery (hereafter referred to as xe2x80x9cblood vesselsxe2x80x9d for the sake of simplicity). For example, catheters are inserted into a patient""s gastric tube for feeding or into an ileostomy for draining fluids to a drain bag.
Some catheters can be directly inserted into a patient, e.g., with an introducer needle, which is withdrawn after insertion, leaving the catheter in the patient. Other catheters, such as a Foley catheter, which is used to drain urine from a bladder, is inserted directly into a patient without the use of a needle. Still other catheters are connected to a patient with a needle that remains in the patient.
Catheters are also used during dialysis, a process that cleanses blood. There are two types of dialysis: hemodialysis and peritoneal dialysis. During hemodialysis, blood is removed from the patient and transferred to a machine, where it is cleaned by filtration through a semi-permeable membrane. During filtration, a dialysate is located on one side of the membrane and blood is located on the other side. Waste particles pass from the blood through the membrane to the dialysate, which washes the waste particles away. Cleansed blood is then returned to the patient.
For more permanent access, before hemodialysis is performed, a doctor can surgically make an entrance into the patient""s blood vessels. In many cases, a doctor surgically creates a xe2x80x9cfistulaxe2x80x9d by joining an artery to a vein to make a larger vessel. Alternatively, a doctor can use a soft plastic tube called a vascular graft to join an artery and a vein under the skin. For more temporary access, a doctor can implant a catheter into, e.g., a large blood vessel in the patient""s neck. After access is made and healed, two needles are inserted into the fistula or graft, with one implanted in a vein side and one implanted in an artery side.
In peritoneal dialysis, the patient""s own peritoneal membrane is used as a semi-permeable filter. Prior to beginning peritoneal dialysis, a doctor implants a peritoneal catheter in the patient""s abdomen. The patient adds a dialysate fluid through the catheter to the abdomen. As the patient""s blood is exposed to the dialysate through the peritoneal membrane, impurities in the blood are drawn through the membrane walls and into the dialysate. The patient drains out the dialysate after three or more hours and pours in fresh fluid.
Peritoneal dialysis is often performed while a patient is sleeping. Where patients turn over or otherwise move during sleep, there is a risk that the peritoneal catheter can unintentionally decouple from the patient. The danger of unintentionally decoupling a catheter connection is particularly acute with patients who, e.g., are agitated or have dementia.
Many other procedures require the secure connection of the sections of tubing or other tubular medical devices such as needles. In many of these procedures, including those described above, it is important to ensure that the connector keeps the catheter connected to a second catheter or to a needle until it is desired to disconnect it. For example, accidental disconnection of a catheter can lead to many serious problems including loss of blood and contamination of the surroundings and/or medical personnel and the cessation of medication delivery. For example, during hemodialysis, if a catheter accidentally disconnects and no intervention occurs, a patient can lose a liter of blood in two minutes and bleed to death in five minutes.
Traditional medical connectors typically include either a threaded connection or a friction fit coupling to connect medical sections of tubing or other tubular medical devices such as needles. In a threaded connection, at least one part of the connector includes threads and the other part includes threads or lugs that are received in the threads. One part is turned relative to the other to make the connection. This type of medical connector is prone to unintentional decoupling. In a fraction fit coupling, a male fitting having a frustoconical shape is inserted into a female fitting having a frustoconical-shaped receiving cavity. Opposing conical surfaces on the female and male fittings come into contact with each other and form a friction fit. This type of adaptor is also susceptible to accidental disconnecting.
In view of the foregoing, it would be desirable to provide a connector that minimizes or prevents accidental disconnection of, e.g., a first piece of medical tubing, such as a catheter, from, e.g., a second piece of medical tubing or from a needle. It would also be desirable to provide a method of connecting and disconnecting medical tubing from, e.g., other pieces of medical tubing or needles such that they do not unintentionally decouple.
The invention, which is defined by the claims set out at the end of this disclosure, is intended to solve at least some of the problems noted above. To summarize, the connector includes a first fitting which is configured to be connectable to a first tubular medial device and a second fitting which is configured to be connectable to a second tubular medical device. The first and second fittings have first and second connections thereon that require the sequential performance of two distinct motions of different direction to couple the first and second fittings to one another. For example, the first and second connections may comprise threaded connections of opposite handedness.
Advantageously, the second fitting may be a multi-component fitting including a ferrule and a sleeve. The ferrule of this fitting may have an outer diameter that is smaller than an inner diameter of the sleeve such that the sleeve can slidably receive the ferrule. In this case, a female portion of the first connection is located on the ferrule, and a corresponding male portion of the first connection is located on the first fitting. Similarly, a female portion of the second connection is located on the sleeve, and a male portion of the second connection is located on the first fitting, inwardly from the male portion of the first connection.
In accordance with another aspect of the invention, a method of coupling two tubular medical devices together includes connecting a first fitting of a medical connector to a second fitting of the medical connector at a first connection in a first motion, then connecting the first fitting to the second fitting at a second connection in a second motion, wherein the first and second motions are distinct and are of different directions. Preferably, the connecting steps include turning the first and second fittings relative to each other with the first set of connections taking place when the fittings are turned in a first direction and the second set of connections taking place when the fittings are turned in a second, opposite direction.